Proximity sensors are conventionally used for determining the proximity to an electrically conductive body, the proximity sensors having a transmitting arrangement with an oscillating circuit. An electrical oscillation at a selected predefined frequency is produced by the oscillating circuit. The electrical oscillation, in turn, produces an alternating magnetic field which is transmitted by a coil of the oscillating circuit and has the same frequency as the electrical oscillation. The transmitted alternating magnetic field is propagated from the proximity sensor and, if an electrically conductive body is located in the region of the transmitted alternating magnetic field, hits the electrically conductive body. An alternating current, which is also known as an eddy current, is produced in the electrically conductive body by the transmitted alternating magnetic field. The eddy current results in an alternating magnetic field which has the same frequency as the transmitted alternating magnetic field.
Such proximity sensors also have a receiving arrangement, by means of which an alternating magnetic field is registered. In particular, the alternating magnetic field which is transmitted back from the electrically conductive body is registered by means of the receiving arrangement. By comparing the transmitted and the registered alternating magnetic fields, for example by comparing the maximum amplitudes thereof and/or the phase shift thereof, the proximity and/or the degree of proximity of the electrically conductive body to the proximity sensor may be determined.
When determining the proximity, however, false values occur when interfering alternating magnetic fields are present in the region of the receiving arrangement, in particular at the same frequency as the respectively transmitted frequency of the transmitted alternating magnetic fields. The interfering alternating magnetic fields may occur, for example, as a result of electric motors or other interfering devices present in the vicinity.